Combustion engines, including gasoline spark-ignited engines, diesel compression ignition engines, gaseous fuel engines, and still others, operate generally by producing a controlled combustion reaction within a cylinder which drives a piston to rotate a crankshaft. This basic technique has been used to operate engines with traditional fuels such as gasoline or diesel for well over a century. Emissions concerns, price and supply concerns, amongst others, have led to increased interest and exploitation of less traditional fuels such as natural gas, hydrogen, landfill gas, and biogas. These fuels typically are used at a higher stoichiometric air-to-fuel ratio, meaning so-called “lean” fuel/air mixtures, or mixtures having an equivalence ratio less than 1, are common. A traditional combustion engine ignition strategy that relies on a spark plug or compression ignition may fail to properly ignite the mixture resulting in engine knock or other problems.
Use of a prechamber ignition device can address these issues by igniting a fuel/air mixture in a prechamber before delivering a jet of hot, combusting gases to the combustion chamber, resulting in a hotter, more uniform, and more robust combustion reaction as compared to other techniques. A typical prechamber assembly is constructed of a base formed of cast iron or steel, with an attached tip formed of materials well-suited to withstanding regular and intense combustion reactions, such as certain forms of Inconel.
One strategy for extending the life of a prechamber assembly is disclosed in European Patent 2,205,840 to Granlund (“Granlund”). Granlund discloses a prechamber assembly having replaceable parts, such as a cover and a tip piece, allowing for repair of corroded assemblies by replacing individual components instead of the entire assembly. While this and other solutions may extend the life of the assembly overall, the disclosed mechanism for doing so requires regular maintenance and there remains ample room for improvement.